PDA

View Full Version : Power Supply Questions and Advice Needed



timellis
06-09-2013, 08:32 PM
I am putting together a cnc based guitar pickup winder and need some help with power. The winder has 2 stepper motors - one rated at 3.4v / 1.68a and the other at 2.8v / 1.68a

How do I power these motors? Do I need 2 power supply's for the different voltages?

Also any recommendations on good, cheap, easy to set up drives and breakout board would be appreciated.

As you can tell, I am very new at this. If this project goes well I am going to build a cnc for guitar body's and necks.

JAZZCNC
06-09-2013, 11:06 PM
If you work a rule of thumb Max 20x the rated voltage of the lowest motor you'll be ok. . . .BUT . . The drives you use may be the limiting factor more than the motors.? . . . For instance if you take the 2.8 and 20x rule then thats 56Vdc so you'll need drives capably handling higher than this value.
Mostly drives come in 2 basic voltage flavours upto 50Vdc and upto 75-80vdc. So if you buy 50V drives then you'll need to run these motors around 44-45vdc Max, you never run at drives maximum rated voltage has steppers generate electricity at times and can pass this back and blow drives so safety factor needs allowing.

Now you don't need to run these steppers at 56v they will happily work at lower voltages like 24-36Vdc but at a reduced speed/torque. Most drives won't work below 24Vdc.

Before recommending a drive, Even thou they will probably easily do what you want for guitar winder I will recommend that you don't buy the cheap TB chip based All-in-one boards has they are very poor quality and can be unreliable, they are also easily damaged in the hands of inexperienced users.!! . . .Stay clear is my advice.

Now if you want to buy drives that can migrate to a CNC machine then you'll want to buy decent drives and not skimp, it's false economy and leads to poor and often frustrating results.

So if just drives for a winder and to test the waters of a CNC machine then I'd say buy any of the cheap Chinese drives like these CNC Mill Router DIY CNC Stepper Driver Board Controller M542 1.0A-4.5A 20V-50VDC | eBay (http://www.ebay.co.uk/itm/CNC-Mill-Router-DIY-CNC-Stepper-Driver-Board-Controller-M542-1-0A-4-5A-20V-50VDC-/400560976357?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item5d434b71e5)

If you want to build a decent CNC machine then I'd say wait and select drives when you know better what your building.!!
Digital drives are becoming cheaper every month and for best machine you'll want these so I'd wait until the time then buy. You'll also know better then if larger motors with higher voltages are required.

timellis
08-09-2013, 12:23 PM
If you work a rule of thumb Max 20x the rated voltage of the lowest motor you'll be ok. . . .BUT . . The drives you use may be the limiting factor more than the motors.? . . . For instance if you take the 2.8 and 20x rule then thats 56Vdc so you'll need drives capably handling higher than this value.
Mostly drives come in 2 basic voltage flavours upto 50Vdc and upto 75-80vdc. So if you buy 50V drives then you'll need to run these motors around 44-45vdc Max, you never run at drives maximum rated voltage has steppers generate electricity at times and can pass this back and blow drives so safety factor needs allowing.

Now you don't need to run these steppers at 56v they will happily work at lower voltages like 24-36Vdc but at a reduced speed/torque. Most drives won't work below 24Vdc.

Before recommending a drive, Even thou they will probably easily do what you want for guitar winder I will recommend that you don't buy the cheap TB chip based All-in-one boards has they are very poor quality and can be unreliable, they are also easily damaged in the hands of inexperienced users.!! . . .Stay clear is my advice.

Now if you want to buy drives that can migrate to a CNC machine then you'll want to buy decent drives and not skimp, it's false economy and leads to poor and often frustrating results.

So if just drives for a winder and to test the waters of a CNC machine then I'd say buy any of the cheap Chinese drives like these CNC Mill Router DIY CNC Stepper Driver Board Controller M542 1.0A-4.5A 20V-50VDC | eBay (http://www.ebay.co.uk/itm/CNC-Mill-Router-DIY-CNC-Stepper-Driver-Board-Controller-M542-1-0A-4-5A-20V-50VDC-/400560976357?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item5d434b71e5)

If you want to build a decent CNC machine then I'd say wait and select drives when you know better what your building.!!
Digital drives are becoming cheaper every month and for best machine you'll want these so I'd wait until the time then buy. You'll also know better then if larger motors with higher voltages are required.

Thanks very much for the reply - I now have a better understanding of my power requirements. With regards to stepper drivers I have seen some that are 3 axis rather than individual for each stepper motor. Is this a good idea or are they not recommended?

Thanks in advance for the advice.

JAZZCNC
08-09-2013, 09:55 PM
With regards to stepper drivers I have seen some that are 3 axis rather than individual for each stepper motor. Is this a good idea or are they not recommended?

No chances are these are the TB based boards I suggest you stay away from. The only multi axis board I recommend is the Gecko G540 which is 4 axis and not cheap but is a high quality unit with good support and excellent warranty.

If you can post linkto what your looking at will take a look.!

~andy
08-09-2013, 10:56 PM
Use 24v and the cheapest drives you can find. It's a pickup winder!

JAZZCNC
08-09-2013, 11:19 PM
Use 24v and the cheapest drives you can find. It's a pickup winder!

That's ok just for winder but he's thinking to use same drives for a CNC machine at later date and 24V ain't much use there.!!

~andy
08-09-2013, 11:41 PM
That's ok just for winder but he's thinking to use same drives for a CNC machine at later date

He will need to over spec the PSU if he wants to reuse it in a future CNC router build (which i don't see him suggesting).


and 24V ain't much use there.!!

Nothing hideously wrong with 24v, just not optimal.

JAZZCNC
09-09-2013, 12:59 AM
He will need to over spec the PSU if he wants to reuse it in a future CNC router build (which i don't see him suggesting).



Nothing hideously wrong with 24v, just not optimal.

No he won't need to over spec the PSU those motors will easily handle 50V so running at 44-45Vdc on 50V drives will be fine for most small to medium machines or winder, so they will migrate nicely when the time comes and he will be getting optimum performance from the drives/motors at all times.

24V on the other hand while perfectly fine for a winder will be very restrictive in speed terms for a CNC machine. TB based 3 axis boards will probably run fine without issues at 24V but they don't like staying alive much after 36V.
The motors are capable of running above 50V so why not have the ability to use there full potential, Better to have spare capacity than be lacking at later date when needed.

~andy
09-09-2013, 01:19 AM
No he won't need to over spec the PSU those motors

He isn't going to run a 3/4 axis router with 2 x 1.68a steppers, so the PSU would have to be larger than needed.

He doesn't say he is going to break his new winder for parts anyway.

JAZZCNC
09-09-2013, 01:29 AM
He isn't going to run a 3/4 axis router with 2 x 1.68a steppers, so the PSU would have to be larger than needed

Only in terms of amps but he'll only pull what's needed there.!! . . . . But yes your correct I am assuming he's thinking to use same motors where he might not.!!. . . But still he possibly could want to use the same drives and if he had 50V drives with 44V 8-10A psu then he easily could do it where has with poxy TB based drives then it start again from scratch.!!

Anyway only he knows where he wants to go we just point out the different directions he can take.!!

timellis
10-09-2013, 05:45 PM
The cnc build at a later date will be with new motors, drives etc. Thanks for the responses they have really helped, especially when it comes to power supply choice. Once I have it up and running I will post some pictures.

EddyCurrent
10-09-2013, 08:40 PM
Going into competition with Bareknuckle :wink:

JAZZCNC
10-09-2013, 09:16 PM
The cnc build at a later date will be with new motors, drives etc.

In which case then Andy is absolutely correct just throw 24v at it cheap has possible and the 3 axis TB based boards will probably be the cheapest route. @ 24v they will be ok, go much higher and they like letting out magic smoke.!

HankMcSpank
11-09-2013, 11:01 AM
I've made a CNC guitar pickup winder previously...& I agree....make it as cheap as chips - the TB based boards are awful, but that's mainly when they are pushed....and winding 0.06mm dia. copper wire onto a bobbin, is not going to stress anything.

Two of these ought to be fine for a CNC guitar winder (overkill, but they're the cheapest option)...

CNC Router TB6560 Single 3.5A 1 Axis Stepper Stepping Motor Driver Board Control | eBay (http://www.ebay.co.uk/itm/CNC-Router-TB6560-Single-3-5A-1-Axis-Stepper-Stepping-Motor-Driver-Board-Control-/221263186859?pt=UK_BOI_Industrial_Automation_Contr ol_ET&hash=item3384504bab)

njhussey
11-09-2013, 12:12 PM
I have a TB6560 3 axis board and 3 Nema 23 steppers as well as a 24V PSU (http://www.mycncuk.com/forums/router-build-logs/2148-comments-sought-new-build-cnc-router-rc-gliders-planes.html)you can have (well buy!!) as a package...bought these before coming on the forum and they'd be useless for my build...PM me if you're interested and I'm sure we could come to some arrangement...

timellis
11-09-2013, 10:10 PM
What software did you use to run the cnc winder?

HankMcSpank
11-09-2013, 10:32 PM
What software did you use to run the cnc winder?

a free program called gcoil ...which you enter a few parameters of your bobbin & it produces g-code for your particular wind.

You then load the g-code into your CNC app.